The present invention pertains generally to the field of playground equipment, and more specifically to a mount or pivot for a certain class of playground swings.
In conventional playground swings, the swing and mount are designed primarily for oscillation throughout an angle in one plane. In another type of swing, oscillatory motion in any direction throughout a solid angle is contemplated. Additionally, rotation of the swing about an axis from the seat of the swing to the mount is sometimes desirable. Swings of this latter type are referred to herein as "tire swings", in accordance with customary usage in the field resulting from the fact that an automobile tire is often used for the seat in such a swing. However, it will be understood that as used herein, the term "tire swing" includes all swings designed for swinging in all directions rather than primarily in a single plane, regardless of whether the seat of the swing is made of a tire or other material.
In general, a tire swing includes a frame or other overhead support,; a seat; ropes, chains, or cable, or possibly a solid member for suspending the seat; and a swing mount or pivot for providing the support and allowing motion between the support and the members which suspend the seat.
In prior art tire swings, various types of swing mounts have been used. These range from a simple hook, eye or pin, to a universal joint. In the case of a simple hook, eye or pin, the only bearing surface provided is the rubbing of the chain of cable on the fixed mount. This rubbing may lead to rapid wearing of the chain or mount resulting in failure. Additionally, unless a separate swivel is provided, rotation of the swing can be accomplished only by winding up the chains or cables which support the seat, and this winding represents a potential safety hazard because children's fingers and hair can get caught in the winding chains.
The use of a universal joint overcomes one shortcoming of the simpler type mount discussed above, in that it can potentially provide longer wearing bearings. However, like the simple mount discussed above, if a separate swivel is not provided, the universal joint will still be subject to the chain or cable winding situation and its attendant dangers. Additionally, due to the nature of its construction, the universal joint has many pinch points which pose a potential hazard. If the children were to stand on the seat or climb up the chains, they could get their hands in the universal joint in such a position that, if the swing were then to the moved, the fingers could be jammed between moving parts of the universal joint. Another problem with universal-type joints, depending upon their individual construction, is that the pivots or bearing surfaces are potentially exposed to the element and may therefore be subject to corrosion resulting in shorter life.